The purposes of this study are to collect data on severe headache in order to measure the prevalence and to describe the demographic characteristics of the major types of headache. To this end a survey of the general population has been designed. A survey questionnaire, which includes sections on demography, descriptive headache features, medical information, and history, has been developed. The data will also be used to identify and assess the etiological and environmental factors associated with the major idiopathic headache types. The study was designed in two parts: a feasibility study and an area survey. The feasibility study has been completed. Telephone interviews have been conducted with the patients from four headache clinics. The questionnaire data have been processed together with information abstracted from the physician records about the headaches. The planning and design of the area survey has been completed; however, the survey has not yet been funded. The first part of this study has been completed.